석산개발사업의 환경영향 저감방안에 관한 연구

Abstract

Rock quarry development and exploitation may result in extensive environmental impacts, but those impacts has not been investigated yet. Although most of quarry exploitation plans were initiated in a local region by individual permissions for small scale developments, those were eventually extended for being expanded. However, the expanding has been arbitrarily conducted without considering overall environmental impacts in the region, resulting in break-down of regional ecological axis and other serious environmental damages. Furthermore, no action for environmental pollution prevention leads to serious environmental impacts. Some of quarry developers have interest only in making profits, and has not often paid attention to restoration after the exploitations. Quarry developments without considering environmental impacts devast adjacent rivers by suspended solids and surrounding environments by dust scattered from the rock quarries. Suspended solid generation per unit area of quarry is 2.6 to 38.5 times higher than other developments such as golf course, industrial and residential complexes. The total suspended solid generation of quarry is also 2.5 to 9.9 times higher than those of other developments. This study was focused on environmental impacts of quarry development upon sediment accumulation and running water ecosystem. In the study, four sites were selected to survey and investigate characteristics of sediments and changes in aquatic macroinvertebrate community. The results showed that quarry development gave serious effects on water quality and ecological life of the adjacent river basin. Aquatic ecosystem was completely destroyed by disappearing all sorts of benthic invertebrates in the region adjacent to the quarry and was gradually restored as the distance from the contaminant source increased. This is characteristically different from the environmental effects caused by the other non-point contamination sources where some species selectively survive and community structure is still maintained. Fine rock fragments from rock quarry exploitation were primarily deposited on the nearby stream. The primary sediments were disturbed by rainfall and then dispersed into a long-distance, resulting in expansion of an environmental impact area. High turbidity was measured in the time of torrential rainfall, especially in the dry season. Those fine rock sediments would affect the aquatic animals and plants. This study clearly showed how rock quarry and related processing plants, batch plant of ready-mixed concrete and cutting-and-polishing plant for building material continuously affect the aquatic ecosystem. To reduce environmental impacts of quarry exploitation, EIA of all development plans should show their supply plans of earth material for construction. Those supply plans may require an appropriate number of quarry for the construction region. Development of quarry site must accompany with comprehensive and regional plans that cover from siting to material supply needs of the region. It is desirable in rock quarry siting to keep quarry development out of upstream area. Considering geographic conditions and ecological environment, it is also necessary to avoid breakage of ridge line and/or ecological axis(green network) that may affect regional natural environment. Most of all it is strongly recommended to keep sufficient distance between rock quarry and stream or river to prevent the stream from inflow of inorganic materials. To actively protect the aquatic environment, effluent of all streams in the quarry area should be induced into one channel that is connected to settling basin. The settling basin should be regularly maintained to achieve high removal efficiency. Controlling capacity of settling basin should be estimated by using a criteria of the intensity of concentrated rainfall of the area to control effectively the suspended solids. More researches and trials are needed to increase solid-settling efficiency of quarry site. To protect the water environment of the quarry area, it is required to install a monitoring system, continuously monitoring the inflow of earth materials into the streams. For a closed quarry, slopes and terrain should be restored to be compatible to the surrounding environment, and disturbed entrance roads and riparian area also should be recovered. Important thing in recovering excavated slopes and destroyed river is ceaseless care and maintaining. Inadequate maintenance on closed quarry may also result in secondary environmental damage. This study suggests that establishment of well-planned pollution prevention system would minimize adverse environmental impacts, and proper and continuous maintenance can effectively prevent environmental impacts induced by quarry exploitation. This study is expected to contribute to the improved management tactics that considers the protection of environment, by providing valuable information on quarry siting, environmental impacts of quarry development and environmental pollution prevention for environmental-friendly quarry development.